I *think* 68k was the previous #2 seller low this decade and the last 50ksomething was Check on It with 57k.
So that would make it the lowest since the week before 2005's Xmas - 50k for Don't Forget About Us.
IIRC, that's the first position to go to 2005 numbers in the t10. But I'm not at home so I don't have my list.
1 Black Beatles 537 (=) -19%
2 Starboy 520 (+1) +20%
3 Closer 370 (-1) -14%
4 Side To Side 296 (+2) -10%
5 24k Magic 295 (-1) -15%
6 Juju On That Beat 262 (-1) -25%
7 Don't Wanna Know 235 (+3) -2%
8 Let Me Love You 234 (=) -13%
9 Heathens 231 (-2) -14%
10 Fake Love 197 (+1) +3%
11 Broccoli 195 (-2) -19%
12 Starving 186 (+1) +2%
13 I Hate U I Love U 169 (+1) -1%
14 Caroline 168 (-2) -11%
15 Scars To Your Beautiful 164 (=) +4%
16 Bad Things 153 (+12) +41%
17 Party Monster 153 (+22) +68%
18 The Greatest 137 (=) +0%
19 Cold Water 127 (-3) -15%
20 Treat You Better 125 (-3) -16%
21-100
21 Unsteady 124 (-1)
22 All I Want For Christmas Is You 121 (re-entry)
23 Can't Stop The Feeling 118 (-4)
24 In The Name Of Love 114 (=)
25 Cheap Thrills 118 (-4)
26 Love On The Brain 113 (+8)
27 Ooouuu 112 (-5)
28 Blue Ain't Your Color 112 (-3)
29 Sidewalks 111 (debut)
30 All Time Low 108 (+2)
31 I Feel It Coming 107 (+17)
32 Don't Let Me Down 106 (-9)
33 Reminder 103 (debut)
34 This Town 103 (-5)
35 Chill Bill 101 (-5)
36 Do You Mind 101 (-9)
37 May We All 100 (-4)
38 This Is What You Came For 100 (-12)
39 Six Feet Under 97 (debut)
40 Ride 96 (-9)
41 X 94 (-5)
42 One Dance 87 (-5)
43 Needed Me 85 (-5)
44 Love Me Now 85 (-1)
45 Rockin 84 (debut)
46 Bad And Boujee 83 (+8)
47 Die For You 83 (debut)
48 Bounce Back 83 (+3)
49 Secrets 83 (debut)
50 All I Know 82 (debut)
51 Mercy 81 (-16)
52 True Colors 80 (debut)
53 Hallelujah 55 (+12)
54 Used To This 76 (-14)
55 False Alarm 74 (re-entry)
56 Sleep Without You 72 (-11)
57 Fresh Eyes 71 (+2)
58 Wanna Be That Song 71 (-1)
59 Pick Up The Phone 70 (-10)
60 Stargirl Interlude 70 (debut)
61 Sneakin 68 (-11)
62 Song For Another Time 67 (-2)
63 No Heart 65 (-2)
64 Nothing Without You 64 (debut)
65 Attention 64 (debut)
66 A Lonely Night 63 (debut)
67 HandClap 63 (-4)
68 Better Man 61 (+1)
69 Love To Lay 61 (debut)
70 Ordinary Life 61 (debut)
71 Say You Won't Let Go 61 (-3)
72 Middle Of A Memory 61 (-14)
73 Tiimmy Turner 61 (-28)
74 Dirty Laundry 59 (-4)
75 Water Under The Bridge 59 (+5)
76 One Night 59 (-21)
77 How Far I'll Go Auli'i Cravalho 56 (debut)
78 That's My Girl 54 (-4)
79 All We Know 54 (-16)
80 Too Much Sauce 53 (-18)
81 Setting The World On Fire 53 (-14)
82 Star Of The Show 51 (=)
83 A Little More Summertime 49 (-19)
84 A Guy With A Girl 49 (+8)
85 How I'll Always Be 47 (+2)
86 How Far I'll Go Alessia Cara 47 (debut)
87 Selfish 45 (-6)
88 Chantaje 45 (-11)
89 Fade 44 (-18)
90 Look Alive 44 (-18)
91 Kill A Word 44 (+3)
92 My Sh*t 44 (+1)
94 What They Want 44 (-11)
95 Distraction 43 (debut)
96 Capsize 43 (-12)
97 Sex With Me 43 (-2)
98 Key To The Streets 41 (-13)
99 Greenlight 41 (-3)
100 Move 41 (-22)
Others
Play That Song 39
Ain't My Fault 37
Million Reasons 37
That's What I Like 36
Rockabye 29
Vice 27
Shout Out To My Ex 25
Slumber Party 15
wait distraction charted so low.... mess all those ads for nothing