MacBook Pro unexplained shutdown when not charging

I have a 2017 MacBook Pro with 2.3 GHz Dual-Core Intel Core i5. It has been working perfectly up until about a year ago. It now randomly shuts down when on battery. The battery % can be anywhere from 100% to 10% and it will just shut down. It is not a normal shut down though, more that the screen goes black and will not come back on until I plug the charger in. Once I have connected power, the screen will power back up and I can log back in as if the laptop had been in sleep. I do get the usual pop up to say 'your laptop shutdown unexpectedly' though.

The attached image is from the most recent 'shut down' I'd be grateful if anyone could shed some light on what this could be mean.

I have done all the usual - resetting the SMC, doing the latest software update. Battery full charge capacity is saying 3608 mAh so not crazy low.

If anyone has any thoughts on what this could be or potential fixes I'd be very grateful. I'm reluctant to pay for a new battery as I'm not sure this is the issue.

Many thanks!

[Edited by Moderator]