Perhaps it is true.

An official from Yahoo Japan said on Feb. 1 that the company decided it has become too difficult to continue servicing the region considering the costs of complying with local laws and regulations.

The company did not specify which laws and regulations it had in mind when making the decision. But it appears to be affected by recent moves in Europe to tighten regulations on the protection of personal data.

Probably a combination of GDPR and the Russian news censorship laws. Otherwise they wouldn't have waited until now to do it. Also if only 1% of their visitors are from Europe, it makes sense to block them rather than to comply with their local laws.