Try to use this script to find out the logs that you may need to restore to the target. Looks like there is a backup job is running while you are trying to establish AG.

If you are not fast enough, by the time you restored the logs, new log backups may be processed again. Try to find that one and see if you can pause it while establishing AG.

SELECT database_name, backup_start_date, type, physical_device_name

from msdb..backupset bs

JOIN msdb..backupmediaset bms ON bs.media_set_id = bms.media_set_id

join msdb..backupmediafamily bmf ON bmf.media_set_id = bms.media_set_id

WHERE

database_name = '<yourDB>'

AND bs.backup_start_date >='fromwhatdate'