Any kind of commercial gain can be considered "profit". 10ct/month from an ad banner is considered a commercial activity in Germany and courts treat it as such,

Any kind of commercial gain can be considered "profit". 10ct/month from an ad banner is considered a commercial activity in Germany and courts treat it as such, with consequences like Impressumspflicht (need to publish personal data, tax number, phone and fax number of the person responsible for a website) and DSGVO applicability. Same for indirect "profit": there have been judgements that considered blogging a commercial activity if the topic of the blog is similar to the dayjob of the blogger because the blog is considered an advertisement to a future employer or customer. Therefore I would consider any kind of open source contribution by an IT professional a commercial activity. Only if the open source contribution is strictly a hobby and your normal job involves nothing IT-like at all you'd maybe be safe.