@River Plate , this below at the end also mentions that 50% 'rule' as it was claimed 2 years ago, but then states that this year it is up to Messi, with no attempt to link the previous claim to his PSG contract. Which is a lot more believable.
La Liga have denied Barcelona's proposal for the return of Lionel Messi, casting doubt as to whether a deal to sign the Paris Saint-Germain star can be reached this summer
www.goal.com
When this was suggested two years ago, someone on here pointed out it wasn't a La Liga rule, but a general Spanish law to stop employees being exploited. And some also claimed it wouldn't apply to Messi back then, as he had terminated his contract and could sign a new one at any amount, i.e it only applied to enforced pay cuts.
Either way, apart from the infobae (whatever that is) article nobody else seems to have tried to link that claim from 2 years ago, to a new player coming from another league/country. Reads like a poor assumption on their part. Given there is an article in a more widely recognised sports paper that suggests otherwise, I feel comfortable questioning it. And am slightly intrigued. Sounds like a lot of excuses being set, but let's see how it plays out.