Hi @Krzysztof Balcerek ,
Questions or issues involving EWS were official recommended to be posted in the Exchange Development forum (according to this link), hence personally I would recommend using some keywords like "EWS" or "Exchange Web Services" and taking advantage of the "Sort" or "Filter" option in the forum page to go through the threads, for example, you could type "EWS" in the search bar and sort the results by "Total Votes":
Then as we can see, the former Exchange Development forum has been archived and migrated to Microsoft Q&A, so should you encounter any future questions/issues related to EWS, you can feel free to post a thread with the tag "office-exchange-server-dev" for assistance.
In addition, the link below covers some content that could you useful when you learn about and work with the EWS Managed API, EWS, and web services in Exchange, hopefully you can find it be of some help:
Explore the EWS Managed API, EWS, and web services in Exchange
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