Too many dots in Safari password fields

Safari 12.0.1 (14606.2.104.1.1) / macOS Mojave 10.14.1 (18B75) / both Mac Mini late 2018 and macBookAir late 2018.

Each time I type a character in a password field, instead of being displayed as a unique dot, it generates lots of dots after a micro-delay. I know it's hard to believe, but in the first example below, I have actually typed one single character; in the second one, two characters:

• Same behavior on any web page with a password field.
• Safari only. No problem on Chrome or Firefox.
• Asking 1Password to fill in the field works. BTW, I thought 1Password was the culprit, but disabling its extension had no effect.
• Deleting type="password" with Safari's inspector makes the problem disappear, but of course that reveals the typed characters.

So I am left scratching my head. Any lead?

Found it, my fault. I had recently defined a system-wide shortcut associating the symbol "•" to another string. Worst idea ever! As soon as a dot appeared, it was expanded to several characters, all replaced by dots, and so on. Since I usually use 1Password, I only hit the issue a few days after the fact.

Now there's something on the internet in case somebody makes the same mistake :)