Google analytics Site kit stops tracking activity,

Thanks for getting in touch @piotrpepson. As there can be a number of reasons why Analytics data stopped collecting for your site, please share the following and we can perform some checks or advise further:

1. Your Site Health information. You can use this form to share privately if preferred.  
2. A screenshot of what you see on the Site Kit dashboard, using the previous 90 days reporting period, using a service such as Imgur or Jumpshare. You can share via the same form if you wish to share this privately.

Let me know if you have any questions with the above.