The crazy and telling truth is it wasn’t all that surprising when the Giants allowed seven sacks in a loss during Week 8 of the 2018 season.

The patchwork offensive line embarrassed by the Redskins that day featured three fill-ins — for injured Jon Halapio, benched-and-cut Ereck Flowers and benched-and-soon-to-be-cut Patrick Omameh.

So, one year later, for a line that has used the same five players on every one of the Giants’ 464 offensive snaps this season to give up eight sacks last week to the Cardinals? That’s not just a step back.

“It caught me by surprise,” Halapio said. “Yeah, we’re angry.”

Left guard Will Hernandez, 24, is the only one of the five starters younger than 28. It’s a veteran group that thought its days — years, actually — holding back the potential of the Giants offense were over.

“We know that just isn’t us anymore,” Hernandez told The Post. “We expect a lot more out of each other and ourselves. To us, that was just unacceptable.”

Only two NFL players, the Cardinals’ Chandler Jones and Buccaneers’ Shaq Barrett, have four-sack games this season. Both accomplished the feat against the Giants within the first seven games.

It’s rarefied air. Since 1982, when sacks became an official NFL statistic, there have been only 31 games in which a single player has recorded more than four sacks, according to Pro Football Reference.

The Giants — who’ve allowed 20 sacks this season, ninth-most in the NFL) — practiced Wednesday in preparation to face a Lions team with just 10 sacks on the season. Only four teams have fewer, and the Giants have 18 by comparison.

“It’s business as usual, but the urgency to block it better is there,” Halapio said. “The focus this week is we can’t do what we did last week or it’s going to be a long second half of the season.”

It would be especially torturous if the Lions are knocking around rookie quarterback Daniel Jones because ex-Giants Devon Kennard (three), Damon Harrison (two) and Romeo Okwara (0.5) account for 5.5 of the Lions’ sacks. The Giants received a total of one fifth-round draft pick for those three players.

“We can complain and give all the excuses we want,” Hernandez said, “but that’s not going to change anything. So, we took it out on practice. We came out and we were like, ‘Screw this. This isn’t us.’ We came out last week and practiced this way and that’s what we got? So, we’re going to practice even harder so we don’t get that [crap] again.”

The Giants offensive line played better after the midseason disaster last year, adding Jamon Brown off waivers as a stabilizer and allowing the then-rookie Hernandez and replacement starters Spencer Pulley and Chad Wheeler to settle in.

This time, the Giants need better results without swapping personnel. Changes are unlikely unless left tackle Nate Solder — a possible trade chip drawing interest — is dealt or right tackle Mike Remmers is benched.

“I don’t think we are playing up to our own standards,” Solder said. “We’re going to work hard the next couple days to improve, to better communicate, to better understand what we are supposed to be doing and what the coaches are asking us to do, and execute it at a higher level.”

The variable of inserting Jones for Eli Manning has made it so the Giants are protecting a more mobile quarterback who can escape pressure. He also holds the ball much longer than Manning, who deferred to check-down passes and throwing at a covered receiver’s feet rather than taking a sack.

“Avoiding sacks is a team thing, and there were a few of those sacks that you would have to attribute to Dan trying to make a play downfield and holding onto the ball,” coach Pat Shurmur said. “There are reasons why they happen.

“I think it’s fair to say we need to do everything better on offense than we did last week. In terms of our expectations, we’ve fallen short and we just need to be more consistent in all areas.”

For more on the Giants heading into the trade deadline, listen to this episode of the Giants podcast, “Blue Rush”: