accounts on YouTube Music are now seeing restrictions on their access to song lyrics, according to multiple reports.

Google began testing lyrics as an exclusive feature for Premium users back in September, but it now appears that this is being expanded on a larger scale. It appears that free users will be limited to viewing lyrics for five songs per month, although confirmation from Google on the number is awaited.
See also: YouTube Music syncs playback across devices
When they reach this limit, users will only be able to see the first few lines. Everything else will be blurred and they will be prompted to “unlock lyrics with the Premium package.” The banner warning users of the limited lyrics remaining appears when someone opens the tab (accompanied by a countdown).
YouTube Music: Limitations on viewing lyrics
This move by Google is part of a broader strategy to promote Premium subscriptions, offering exclusive features that are not available to free users. YouTube Music, as a music streaming service, is trying to differentiate itself from its competitors, such as Spotify and Apple Music, by offering unique features and content.
See also: YouTube Music makes it easier to like

Limited access to lyrics may disappoint many users who enjoy singing along to their favorite songs. However, Google hopes this change will encourage more users to subscribe to Premium, which also offers other premium features, such as ad-free listening and the ability to download songs for offline listening.
The decision to place lyrics behind a paywall is not unprecedented in the music industry. Many platforms are trying to find new ways to increase their revenue and provide value to their subscribers. However, it is important to note that the success of this strategy depends on how attractive the features offered are to users.
See also: YouTube Music Supermix: What is it and how to use it?

In the meantime, users who don't want to pay for Premium can look for alternatives to viewing lyrics, such as independent apps or websites that offer free access to lyrics. However, these solutions may not be as convenient as the experience offered by YouTube Music.
It will be interesting to see how users react to this change and whether there will be an increase in Premium subscriptions. Google continues to invest in developing and improving its services and this move is just one part of its strategy to remain competitive in the music streaming market.
