I'm wondering if this is a systemic thing or just me. I keep my DMs open so my customers can DM me with questions. It used to be rare for me to get spam messages (maybe once every few weeks?), but over the past few weeks it has become more frequent, and now I'm getting spam messages daily (3 so far today). Most of the spam messages are about hiring for part-time jobs and have the same basic message structure, so it seems like Twitter should be able to easily identify them as spam, since I've reported them.
It's not just you. I'm also getting several a day at this point, both the job spam you describe and also a crypto phishing campaign ("here's my username/password on a fake wallet site, please help me recover my funds"). Used to be far less frequent, and more often caught by the spam filter.