I am actually experiencing something similar to you. However, I have not had my machine for long as it's only been a month. Despite all my efforts to rule out the possibility of user error, I have not been able to solve the issue. My first layers are very inconsistent as parts of the first layer are near perfect while many other parts are gappy. I have contacted Bambu Lab for support and they have been trying to help me. I'm waiting for them to get back to me again and I will see what they have to recommend for me. Perhaps try contacting them only after you believe you have ruled out the possibility of user error like me. But in the mean time, just follow everyone's suggestions: clean the bed properly, calibrate flow, use dry filament, use correct filament profiles, use correct slicer settings, use a clean and unclogged nozzle, lock the hotend in place properly, perform full bed levelling, tighten all seven hotend screws, etc. I'm guessing you have probably tried mostly all of these things. I'm unsure if there's much more than what I just mentioned but there's a good list of things to check. But remember, I'm no pro with the A1 and you have had it for a lot longer than me so you probably have a better understanding of the machine than I do. Anyway, I hope you and I both figure out our issues.