Not submitting ampersands in artist, album and track names is one of the known issues with the internal scrobbling option in Deezer, see the related FAQ on the Last.fm support forum for a workaround with external scrobbling apps:

Deezer Scrobbling - Get Help / Tips, Guides, and FAQs - Last.fm Support Community

If you are a Last.fm Pro user, you can also edit the wrong scrobbles in your library and enable the auto-edit feature, so the next playback of the same song should not be broken anymore.

So when is a real fix in Deezer coming for this issue?

Hi @Domagoj Hranjec, thanks for your message.

Indeed this is a Known issue, when tracks have special characters, Last FM don’t get those tracks played on Deezer.

Example - When a album have "+" or "&" Last Fm don't scrooble it.
We are working on a fix but we still don’t have an estimate date for the release of that fix.

Missing an ampersand still submits the scrobble to Last.fm, but creates a new wrong page on Last.fm. Songs, albums and artists having a plus or equals sign will not be submitted at all to Last.fm, so you can only scrobble them afterwards with manual scrobbling tools like Open Scrobbler etc. Also additions in brackets to a track name will usually be omitted which will result in too many scrobbles for the same track, but no scrobbles for the one with the detailed description, e.g. on Super Deluxe editions with unreleased alternative tracks like The Beatles.

Working on a fix would be great news indeed, as the internal scrobbling option is the only way to scrobble on iOS devices for Deezer users due to Apple’s restrictions for external third-party apps, so only very few streaming sites offer this internal feature, not even Apple Music themselves. This can be a plus point for Spotify iOS users who are looking for alternative streaming sites as well, e.g. with a better audio quality.