PS4 games may have 'unexpected behavior' when playing on PlayStation 5

New info from PlayStation.com source code may reveal tidbits about the PlayStation 5's backwards compatibility support with PS4 games.

According to source code found on the PlayStation 5's console checkout page, PS4 game playback on PS5 may not always be a smooth experience. The code mentions many instances of the PS5 and outlines bullet points/info on specific features and warnings about the console itself.

The page specifically says not every PS4 game will be playable on the PS5, which is something Sony already confirmed. Sony's Jim Ryan said 99% of PS4 games would be playable on PS5. OS updates are required as more PS4 games are added to PS5's BC functionality. The full selection of these games may not be boosted, however; the code also says certain games are marked as "boost mode enabled."

Another interesting tidbit is that certain PS4 PS Plus games may not be fully compatible on PS5. The site didn't go into detail on what features won't be available, but this may extend to online play capabilities, and just because a PS4 PS Plus game is playable on PS5 doesn't mean other things like online play are supported.

Here's a list of the things we found from the source code:

• "You might experience unexpected game behavior while playing this PS4 game on PS5 console."
• msgid_free_ps5_digital_upgrade":"Free PS5 Digital Upgrade","msgid_free_ps5_upgrade":"Free PS5 upgrade"
• msgid_only_ps4":"Playable on PS4","msgid_only_ps5":"Only on PS5"
• "msgid_play_game_ps5_system":"To play this game on PS5, your system may need to be updated to the latest system software. Although this game is playable on PS5, some features available on PS4 may be absent. See PlayStation.com/bc for more details."
• "msgid_ps5":"PS5","msgid_ps5_boost_enabled":"PS5 boost mode enabled"
• The games included in the subscription, the online features of each game, as well as the other features and benefits of the PlayStation Plus subscription, are subject to change. Continued access to PlayStation Plus features and benefits requires an active subscription. Service availability not guaranteed.rnrnWhen playing PS4 games on PS5
• Continued access to PlayStation Plus features and benefits requires an active subscription. Service availability not guaranteed.rnrnWhen playing PS4 games on PS5, some functionalities available on PS4 may not be available