This is because of the thermal pads bleeding silicone oils through those holes. Not really an issue.

I had the same issue after upgrading to v7.14. I had to use Netinstall and the reset switch on the card to downgrade back to 7.13.5 to get stability back under Proxmox. I got exactly the same issue. If I upgrade to a version later than 7.13.5, I get weird crashing issues under the latest proxmox 8....

It works fine for me, this switch accepts all kinds of generic SFPs (and SFP+) I have and work reliable, no guarantees ofcourse with third party accessories. The only issue I found has been overheating with some generic 10GBase-T SFP+. Make sure it is updated to the latest FW version.

Support team occasionaly drops by and answers a random question or two. But if you really want your answer, ask them via e-mail address support@mikrotik.com ...

Thanks. I will drop them an email

I’m also curious about this. Could you let us know the answer from support?

This is most likely due to leaky/dead capacitors, making the device not able to start. Those can be easily replaced if you have a soldering iron, or find someone to do it for you. Parts should cost only a few cents.

Usually if a inductor burns it’s because of an overcurrent situation. I would check for shorts in the components surrounding L2. As for the value of L2; I would guess something like 1uH. But only Mikrotik can answer that since there are no schematics available.