im playing androind POCO F5 PRO, OS ver. 2 android ver. 15 AQ3A. Initially im playing as guest and decided to merge/linked it to my email but after signing out i cannot retrieve my account and worst i cannot log in to the battle.net and trapped to logging-in. my internet connection is fine, mobile and wifi. The only thing i could confirm is that, i can play using my apple devices…so i think this is by device issue between android and apple. TYIA.
Look on the battle net site and see if you can link devices in your account settings maybe?