Solution:-
Please be assured that we checked and though the MySQL downgrade is not feasible once the MySQL version is upgraded. However, we did this workaround. Updated the required MariaDB version in: app/etc/di.xml
from
<item name=”MariaDB-(10.2-10.4)” xsi:type=”string”>^10.[2-4].</item>
to
<item name=”MariaDB-(10.2-10.5)” xsi:type=”string”>^10.[2-5].</item> and that fixed it.