AirPods 2 Pro disconnecting and reconnecting during cell phone calls when "automatic ear detection: disabled"

After two months of searching and not finding any solution, let me share with you the issue i had with my iPhone 15 Pro with Airpods Pro 2.

symptoms:

• airpods disconnecting during cell phone calls (quick disconnect, phone switched to speaker, then after few seconds it reconnected)
• no issue with teams / whatsapp calls, podcasts or music
• latest FW (various ios 18) in both phone and latest airpods fw
• regardless if apple watch and mac or apple TV were reachable
• regardless of LTE vs 5G
• ⁠was happening only when „automatic ear detection: disabled“ was chosen (my fav option). when you enabled that, calls were not disconnecting
• ⁠this was not happening with other iphone (iphone 13 of my girlfriend)
• regardless if MIC was set for left/right or automatic
• other bluetooth headsets were working fine
• i did factory reset of phone + restore, didn’t help
• factory reset of airpods, re-pairing
• opening case with apple support didn’t help. instead of getting log files from the phone, they just referred me to apple store
• apple store just grabbed my airpods and after one week they gave me new case, but they said airpods are fine and gave them back to me.
• ⁠in the meantime new minor release of ios was released. that didn’t solve the issue too.

resolution:

I tried one last step. Factory reset of iphone without restore. That was pretty painful since i had to setup all the MFA, banks, etc and install all apps manually... But that seem to resolve the issue.

Obviously the iphone was having some glitch in the backup restore file doing this.