Release 2.0 is not PHP7.4 ready, it is PHP7.4 only

[func0der]

1.0.0...2.0.0#diff-5ed4b47731e717f07a3247ac037aae01d62130c3e5de65b167d7ed232447ef04

Added typed properties, which are PHP7.4 only, which makes the 2.0 release compatible with 7.4 only.
Maybe there could be a new 2.0.1 release with PHP7.4 as the requirement in the composer.json.