Is there anything you think they might have done which could cause that? Anything related to chain tension, etc?
Big one that comes to mind is maybe your derailleur was out of whack, so
"you keep on using that gear. I dunno think it means what gear you think it means.". If the index adjustment were off an entire gear width (or enough to force the shift), that could mess you up a bit. Does the highest gear now feel like what the second-to used to?
Actually no, that would mean you'd have one less gear at the top now if it was that far off... I now (didn't used to) whenever I take the rear wheel off do a derailleur alignment, so that's the first thing I think of.
Hmm, proper alignment / lubrication wouldn't have that big an impact on delivered power I wouldn't think... If you needed brake work maybe the rear brake was dragging and somehow sucking down more motor power? That's a wild guess and likely not it.
In the highest gear / smallest cog is the bike now faster or slower? Were you running it unlocked / speed adjusted before? No, you said same settings so I assume that's what you mean. I wonder if they screwed up your derailleur like my LBS would? I'd elevate the bike and test to see if it's delivering the full range of cogs across all gears. Maybe instead of adjusting it, they messed it up -- which can happen inadvertently. As I've said there's a reason normal people don't trust derailleurs and end up "afraid" to even shift. You do ANYTHING to the back-end you make sure it's still adjusted right.
Hell, given my distrust for derailleurs I'd suggest double checking it at least every 200 miles. Again, cannot sing the praises of Park Tools instructional videos for stuff like that.
I'm not too familiar with the Pace, I've seen one in person and... that's about it. This is my third e-bike
(after two returns of another brand) and I'm playing catchup on bike tech after a two decade hiatus.
But with my Aventure bone stock assist 4 and 5 did race out from under me easily, and why I fast-tracked the planned chainring and crankset swap. I almost pulled the ones off my old cruiser out of impatience with the shipping. PAS 4 and 5 delivered a max of 20mph and 32mph "unlocked" and with the chainring and cassette swap they're now giving me 22 and 35 respectively with no more of it "applying more power than I'm pedaling" since my cadence is lowered in the same gears. Thus assist 2 in 5th gives me a "Safe" 10mph for more crowded routes at a very leisurely pace at the pedals. It also seems to have given me about 10% more range on the battery since I'm now able to apply more muscle across the entire power and gear range.
Flat out stock in assist 5 zipping up/down route 12 here from Keene NH to Troy and back (11 miles) left me with 5% power round trip. After the swap I'm not just going 3mph faster, I'm also ending up with around 12% battery left. Up a "rail trail" that in assist 3 left me at 50% power remaining (at 18mph), I'm now seeing around 60% (at 20mph).
It's all about "wattage" and if the motor is "racing ahead of you", you're using all the motor's wattage and none of your own. And it's why turning down the motor just means not using the bike to its full potential. If it has more power available, use it instead of neutering it.
Really though that's the only two things I can think of that would/should change that without changing out the cogs. The derailleur being set different -- be it properly set now or out of whack by accident -- or they mucked with the controller settings. That said it was my experience that with the Aventure PAS3 and up tended to race out in front of me even in the highest gear, so if your Pace wasn't I'd assume something was actually wrong with it.
But again, I'm no expert on the motor controller side --
even if things like the lack of strain reliefs on cables and exposed wiring on the belly are leaving me unimpressed. -- and playing catchup on the mechanicals. Still learning. Even though it would crush me financially, I've been thinking on picking up a mid-drive just to learn the differences.
Might do it as a DIY. Probably throw my video card fund at that since it sounds like nVidia are going to be dirtbags and delay the 4000 series launch to milk post-crypto crash overstock, Intel's ARC sounds dead in the water, and AMD's stock for anything better than what I have is a joke.
I dunno, it's that or fast-track my plan to build a camper trailer for the bike.