Sendgrid bounces don't match what is getting flagged in Mautic

Product Support
1

Your software
My Mautic version is: v2.15.3
My PHP version is: 7.2

Your problem
My problem is:
I have turned on bounce management for sendgrid on a few accounts and noticed that the bounces recorded in Mautic are x5 of what they are in Sendgrid.
I will look up a contact that has read the email and has bounced, their email has gone through successfully in Sendgrid but has been recorded as a bounce in Mautic.

I have no other bounce management systems in place other than Sendgrid

I suspect its related to soft bounces, where Sendgrid will attempt 3 times until it fails but sends back the first bounce regards which is flagged in Mautic as a Bounce (DNC)

ie 552 5.2.2 The email account that you tried to reach is over quota
This is a 5xx error but is really a soft bounce recorded in Mautic and successfully delivered in Sendgrid

These errors are showing in the log:

Steps I have tried to fix the problem:

2

Thinking “dropped” might be a better option than the bounced

Although the feedback will be delayed 1 send broadcast, will mean that Sendgrid will be mirroring the actually managed bounced list rather than all bounces (soft/hard)

Alternative thinking would be to use Integromat and sync the managed Sendgrid bounced list via API on a daily cycle