A BIOS update on a laptop if power is lost won't just fail if the battery is working. Some models just won't let you START the update if AC power isn't connected because the process can sometimes be so buggy and slow that your battery might run out if you weren't smart enough to do it with a full charge. But it's not going to just stop in the middle of the flash process because you unplugged it, which would absolutely leave it in a non-functional state just like unplugging a desktop during an update.
And just because you had one bad drive doesn't mean all from that brand are something to stay away from. You're just as likely to pick up one bad drive from Samsung and not know until you get it home and test it then go searching for known issues just like you did with the Verbatim drive.
I had to dig deep to find a reference to this issue, since you didn't specify the model of the drive. They use the Store 'n' Go brand for a large number of drives, as well as Store 'n' Click, Store 'n' Stay and Store 'n' Save, but there's no such thing as Plug 'n' Go. This post is the only result for "solves disconnection issue" associated with Verbatim. (Their support page sucks butt, too. After searching if you click "view support documents" you can't go back to your search results because it's not just a link to a page but Javascript and you have to search again.)
External USB drives don't require any additional drivers, as they are a standard interface used by all drives which has drivers built into every OS for the last 20 years. I finally found the Store 'n' Go Mini SSD USB 3.2 Gen 1 512GB has a FIRMWARE update that fixes an issue with the drive unmounting after 5 minutes of inactivity. That just means there was a flaw in the firmware, which can happen with any device. Every company has flaws/bugs in their software and firmware, and the fact that Verbatim has fixed it is a good thing, not a reason to avoid the brand entirely.
I scanned the updater with VirusTotal too, and only 13/66 vendors reported possible malware. Only 7 of those vendors are any I've ever even heard of, and most of them are reporting "generic" or "potential" trojans (if their report ID even means anything at all that can be looked up) which means they just think the code looks similar to malware code, not that it actually is detected malware. (Google just reports "detected" which means nothing.) Avoiding fixing the drive based on this VT report means throwing away a perfectly good SSD. VirusTotal isn't a magic oracle that knows all.