Eventually it can't scale any higher.

Boss Blind on Ante 38 is 1.800e289.

Or a score of 180,000,000,000,000,064,536,256,024,536,408,872,920,592,704,128,808,736,640,952,448,784,984,256,024,560,504,544,872,312,000,096,496,112,320,056,824,952,424,544,776,104,936,088,568,728,128,496,448,608,712,800,336,504,488,880,712,656,616,240,528,032,112,792,640,912,168,432,120,448,672,096,528,240,016,376,496,824,144,016.

Small Blind on Ante 39 is NAN.

If you use cheats to brute force the most effectively scoring hand possible in Balatro you score also NAN and the game declares that a failure, ending the run.

Oh I'm sorry I fucked up the previous calculation.

The Boss Blind in Ante 38 is worth a number larger than the Plurk character limit.

17,999,999,999,999,996,904,696,640,856,248,712,296,296,112,960,304,000,168,312,648,936,272,192,496,552,864,672,528,800,952,048,432,200,032,032,816,656,296,120,728,920,224,968,688,896,560,328,456,664,048,928,240,904,280,912,528,944,408,248,704,632,472,544,352,816,912,728,312,000,792,912,368,824,424,600,

552,440,832,824,600,384,040,240,648,448,424,472,776,784,696,272,792,928,232,632,560

The Skull Joker also can't save you because 25% of infinite, which is what NAN effectively is is also infinite so you scoring infinite means you don't reach infinite or a fraction of infinite since that's impossible.

In summary Ante 39 in Balatro is this numerically: