They can't hear me

its an issue with the lower microphone signal.

could be plugged: A dirty port causes issues with sound coming through, to the point of a plug, which will fully block the sound altogether. Take a paper clip, and wiggle it around in the microphone hole to try and clear out some debris. Scrubbibg with a toothbrush and 99%isopropyl helps as well

Could be a bad mic: if cleaning doesnt fix your issue, your next step is to fully replace the board flex with the microphone on it. if this fixes your issue, your flex was bad.

Could be a software issue: if the above doesnt fix your issue, you should attempt a full out factory reset as a last resort. this will fully reset your software, and erase ALL third party data.

Could be a board failure: if the above doesnt help, you likely have a failing board. Logic board replacements can get pretty costly.