You most likely have a hardware issue of some sort. Make sure to disconnect all external devices in case one of them is causing a problem. Otherwise you will need to have the laptop repaired which will most likely involve replacing the Logic Board.
I believe at one time Apple actually had a free Logic Board repair program for the MBAir 2018 model, but I don't see it listed on their publicly acknowledged list of free repair programs. This means either it is expired, or it was (or is) a secret free repair program. Most Apple free repair programs are only valid for up to three years after purchase (some may be four years...it is rare for any to be five years these days). Many times Apple techs overlook the secret repair programs because they are noted in a different location (Apple doesn't make this easy for anyone...techs or users).
Depending how the battery repair was performed you should have a 90 day part or repair warranty so you should go back within that 90 days. I don't know why any tech would replace a battery for this problem especially when they should be aware of the Apple free Logic Board repair program (not all 2018 MBAirs qualify even if you have a failure...it is based on system serial number). Unfortunately Apple does not instruct their techs to look at Kernel Panic logs so unless a diagnostic gives them an error code, techs must resort to a best guess for which part to replace (Apple's service guides do provide suggestions, but not all issues fit neatly into a category).
FYI, this laptop does not have a proper cooling system installed...most techs which see this laptop laugh at it knowing Logic Boards will be burning up due to inadequate cooling. While this laptop does include a fan for active cooling, the heatsink for the CPU does not include a heatpipe which typically extends in front of the fan. The heatsink and fan are not next to each other on this laptop so the fan is not blowing air directly across the heatsink for optimal cooling. This is apparently what "Think Different" means today.
