SharePoint 2010 Workflow getting stuck and locked in SP 2019

I am facing several challenging after migration from SharePoint 2013 to SharePoint 2019, the major challenge facing now is for SPD 2010 workflow.

  1. The WF is designed in SPD2010, while it is running on SharePoint 2019 server.
  2. It is list WF, and targeted on a document library, it should trigger when any document is uploaded, some metadata is required at same time like 1st,2nd,… approvers where 1st is mandatory
  3. There is also an event receiver targeted to that library, and its job is to trigger the WF when a document is created
  4. When a document is uploaded, I have created a step in WF, which will wait for 1st approval then only continue forward and a task should be created.
  5. A mail is triggered on successful creation of task.

Now the issue I am getting in the above process

  1. WF is not triggering,and when I try to start manually it takes atleast 2 try to start the WF
  2. For the same we have created a script in C# which trigger all suck stuck WF and same is happening like taking atleast 2 try to start the WF
  3. Now when the WF is triggered, now a task is assigned to approvers, but when approvers trying to approve the task, the task is not getting approved in 1st try(most of the time) and when they try again the task is getting locked.
  4. For unlocking the WF, we have a PS script, which unlocks all ‘Not Started’ and ‘In Progress’ Tasks.

Please suggest how could I troubleshoot the issue, as not getting any clue what to try