My iPhone 11 just had a battery replacement but is taking forever to charge

Hi, so I just had my iPhone repaired after being stuck in a boot-loop for 24 hours. The repairmen had to wipe the phone because the restore would not work unfortunately, but afterwards they were able to hook it up to their software to determine the cause of the crashing since it was still boot-looping even after being restored. They found out that the battery was absolutely fried and had been installed incorrectly by the previous repairman I took it to a couple days earlier (for the same problem), the power flex something or other was damaged, and a thermal sensor was damaged as well. I trust them completely, I've never had any issues with them whereas every other repair store I've gone to has been pretty terrible. We don't have an Apple store in my city, so we just have to make do with locals, which is fine.

However, I just got my phone back and they said that it held charge for a while and seemed to be working fine again so they put it into the box for collection. I wasn't able to pick it up for a while because I've been using an iPhone 6 and it's been horrendous so I must've missed the notification. Thus, it went flat whilst it waited for me but I told them it was fine as long as they tested it and were happy with it, I'd just charge it at home. It's been charging for upwards of an hour now and it's turned on twice, both times sitting at 1% and then dies again as soon as I touch it. It's definitely charging, otherwise it wouldn't turn on and it wouldn't display the low battery screen. Is this normal for a new battery? I've not had a battery change on this phone since I got it in 2020 (well overdue), so I don't know if it takes a while to start up or not. It's taking longer than my iPhone 6 took to turn on and that thing is about 8-9 years old, so I'm confused whether this is normal or concerning.

Happy to provide more info if needed, thanks in advance :)