Upgrade version EE version 2.9.2 to 3.5.6 are not allow open/edit entry and showing memory issue

Hi there We are facing an issue on our running job site where we have upgrade version EE version 2.9.2 to 3.5.6. Now we are unable to do edit/create/open entries and as well as create new channel fields. We have huge database where about 600000 channel data and 100000 members and in future it will be increase. During upgrade process all module, plugin and extension have upgraded successfully. Below is error Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 72 bytes) in system/ee/legacy/database/drivers/mysqli/mysqli_result.php on line 194 Also after deletion of member group site is working fine.Please let me know if you needed any further information. Thanks in advance