It's fair to believe this, given there's so much material out on the web affirming the fact. I've written about this at length in other places; applications with Electron pre version 5 [0] (released April 2019) were not secure. It's entirely possible and easy to build a secure Electron app today. I started building a secure app Electron template in 2020 [1] (that I still maintain) to address this security issue. I've also written about a history of the framework [2] and steps to build your own Electron app with today's best practices [3].
[0] - https://github.com/electron/electron/releases/tag/v5.0.0 [1] - https://github.com/reZach/secure-electron-template [2] - https://www.debugandrelease.com/the-ultimate-electron-guide/ [3] - https://www.debugandrelease.com/creating-a-simple-electron-a...