MR discussion diffs unreadable with OWA email client

This started happening recently, but I don't recall exactly when (sorry). We are a Premium customer tracking the current GitLab releases (at 15.0.2-ee today).

When viewed in the Outlook web mail client, GitLab-generated emails in response to MR discussions show diffs with an unreadably tiny font. It seems this is an interoperability issue specific to GitLab and the OWA (Outlook on the web for Exchange Server 2016) email client: If I forward the same message to a gmail account, gmail renders it legibly, and if I view the message in a different Outlook client (the "Nine" Android app), it's readable.

I don't know if the OWA client is buggy, or if it is interpreting the HTML/CSS standards more strictly than the others. Either way, I suspect it will be easier to adjust the formatting of the emails sent by GitLab (an agile, customer-responsive organization) than to change the Microsoft OWA client. ;-)

Here is an example of how OWA renders a diff (the black bars are part of the rendering issue, not redaction):