Git fetches whole repository and not just latest

A bit of description what I have on my side. So, I have a local repository which has many remotes added (~20 or so). Most of them are from the same Git server, but few are from different servers.

To refresh the state of my local repository I run `git remote update -p`. One note that I'm behind the proxy. This schema works for few years until out of a sudden (approximately month ago) I have noticed that Git started fetching whole repository instead of only latest stuff. Note, that the repositories in question are from the main server. Yes, sometimes it goes well, sometimes some random repository gets downloaded in full.

Example:

(few days ago)

Fetching spi remote: Enumerating objects: 18064, done. remote: Counting objects: 100% (18064/18064), done. remote: Compressing objects: 100% (2784/2784), done. remote: Total 7343589 (delta 16227), reused 15523 (delta 15266), pack-reused 7325525 Receiving objects: 100% (7343589/7343589), 1.21 GiB | 2.36 MiB/s, done.

(today)

Fetching spi remote: Enumerating objects: 822, done. remote: Counting objects: 100% (686/686), done. remote: Compressing objects: 100% (323/323), done. remote: Total 602 (delta 485), reused 358 (delta 279), pack-reused 0 Receiving objects: 100% (602/602), 160.25 KiB | 896.00 KiB/s, done.

(also today) Fetching origin remote: Enumerating objects: 17806, done. remote: Counting objects: 100% (17806/17806), done. remote: Compressing objects: 100% (2681/2681), done. remote: Total 7343331 (delta 15992), reused 15321 (delta 15106), pack-reused 7325525 Receiving objects: 100% (7343331/7343331), 1.21 GiB | 7.59 MiB/s, done.

origin, for example, almost everyday now gets in full (1.21 GiB!), while others have no pattern.

I would like to know if it's problem of proxy, or that specific Git server or is it (new) bug in Git?