tptk vs river donk

Hand converted with online PokerStrategy.com hand converter:

Play hand

$0.25/$0.5 No-Limit Hold'em (6 handed)

Known players:
[tg]BU$55.54:///////;SB$107.11:///////;BB$50.00:///////;MP2 (Hero)$50.00:///////;MP3$51.82:///////;CO$96.40:///////;[/tg]

Preflop: Hero is MP2 with K:d, A:s.
Hero raises to $1.75, 3 folds, SB calls $1.50, BB folds.

Flop: ($4) T:d, K:s, 6:c (2 players)
SB checks, Hero bets $2.50, SB calls $2.50.

Turn: ($9) 2:s (2 players)
SB checks, Hero bets $5.50, SB calls $5.50.

River: ($20) 8:s (2 players)
SB bets $20.50, Hero calls $20.50.

Final Pot: $61.
Opponent is 47/27 191 hands
AFq 51%
WTS 43%
3Bet PF 16% (14/87)
Fold to CB F 20%
ch/r F 20% (3/15)
Donk F 20% (3/15)
There are not many value combinatins on the river which could act such a way, but I'm not sure.