MacBook Air running slow after battery replacement + software upgrade

Hi! About 3 weeks ago I brought my MacBook Air to an Apple store to have the battery replaced. They also deleted a bunch of stuff to make space for the latest software upgraded and then did the upgrade to Monterey version 12.6. Ever since then my computer has been running really slowly, which has been affecting my work since I work online. I live abroad in a pretty remote place (I was visiting family in the US when I brought it to an Apple store) and there is a technician here who specializes in Macs but I wanted to see if I could do something to fix it myself before bringing it there, especially since I don't trust 100% in the service here and don't want to do anything that could make it worse since I depend on it for work. Thanks for any help you can provide!